Geographical location data have been widely applied in various application fields. A plurality of application products about the geographical location data have been developed to provide services to users. A fundamental technology behind these services is electronic map technology. An electronic map is a map stored and reviewed in a digital manner. A method for an electronic map to store information typically uses vector-type image storage, where the map size may be scaled up, scaled down, or rotated, without affecting the display effect. Bitmap storage was previously used, where the map size could not be scaled up or down.
Modern electronic map software typically uses a geographical information system to store and transfer map data. Other information systems may be used. In an electronic map, every place in the world may be searched and browsed. Electronic map services comprise: map browsing, address search, geographical location surrounding search, drive route search, bus route search, satellite picture browsing, scenic picture browsing, and positioning and navigation, etc. Some websites even provide dedicated electronic map services for sightseeing, hotels, and house renting information. An electronic map has currently become an important application technology that is indispensable in daily life.